1. Technical Field
The present invention relates to a propeller shaped agitator, in particular to a propeller shaped agitator having blades, blade roots and hub segments.
2. Discussion of the Related Art
In various technical areas agitators are employed for mixing, transporting and retaining of substantially homogeneous fluids. Frequently this involves a multibladed propeller shaped agitator the hub of which is coupled to a driving source.
A particular useful process for the circulation of fluids which may also contain solid material, involves the employment of submerged motor agitators. In the case of these agitators a driving motor is directly coupled to a propeller shaped agitator and is totally submerged in the fluid to be agitated. The propeller agitators can hydraulically transfer very high impulse forces, through which it is possible to maintain large basin volumes in continuous motion, as in clarification technology for example. At the same time the solid material particles in the volume of the fluid can be held in suspension thereby, and a settling of these to the bottom of the basin is prevented. Propeller shaped agitators known in the art typically have diameters up to three meters. For ease of fabrication, such propellers are usually made of composite construction, in which the propeller blades are formed as a plastic element. A metallic propeller hub and/or propeller shaft with the help of reinforcing elements, supplies the necessary large driving turning moment to the individual blades. High bending forces are developed in the transition region between the hub element and the blade roots. Not withstanding the use of reinforcing elements in the transition region, there is still a problem of frequent breakage of the propeller blades. The basis then for the present invention is to prevent the breakage of the blades in propeller shaped agitators employing plastic blades and the resulting disadvantages which arise therefrom.